Our brains are charged with the monumental task of combining information across multiple sensory systems into a coherent picture of our world. Because we rarely process a single sense in isolation, any realistic neural model of perception must address how the brain combines sensory information on a moment-to-moment basis. Of particular importance to human communication and the focus of this proposal are the neural underpinnings of audiovisual interactions. Despite the prevalence and importance of vision in human communication, little is known about how the brain uses visual information to constrain or even change what we hear. For instance, visual spatial information is extremely precise and tends to dominate relatively imprecise auditory spatial estimates, giving rise to the ventriloquist's illusion. Here, we propose two complementary studies that use the ventriloquist's illusion as a tool to determine how changes in interregional communication (Experiment 1) and temporal precision of neural activity (Experiment 2) relate to vision's influence over where we perceive sounds in space. PUBLIC HEALTH RELEVANCE: The proposed project addresses how the human brain uses visual information to refine or constrain where we perceive an auditory object's location to be. The findings will have a direct impact on current models of human speech perception and existing models of audiovisual integration in humans.